Evaporative emissions of hydrocarbons from motor vehicles when parked are a known environmental issue. Evaporative emissions may be caused when small quantities of fuel vapour flow from the engine in a reverse direction along air induction conduits of the vehicle and out from an air intake of the vehicle.
One way of reducing or preventing evaporative emissions is to provide a hydrocarbon trap in the air intake of the vehicle. It is known to provide a flow-through trap in the form of a membrane of a hydrocarbon-trapping medium such as a sheet of activated carbon in an air filter compartment of a vehicle. Flow-through traps have the disadvantage that a back pressure is developed on air being drawn through the trap.
It is an aim of the invention to address this problem. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.